Ulster Unionist leader Mr David Trimble tonight won a crucial vote at his party's ruling council on the British and Irish Governments' joint plan for the Northern Ireland peace process.
Mr Trimble defeated a motion proposed by his main rival Mr Jeffrey Donaldson calling on delegates to reject the joint declaration released by London and Dublin last month.
In a tense vote at a south Belfast hotel, members of the Ulster Unionist council supported Mr Trimble as hard-liners tried to force him into an outright rejection of the Dublin and London peace process plan.
Hard-line Ulster Unionist MP Mr Donaldson had threatened to leave the Ulster Unionist Party if the vote went against him.
Ulster Unionist sources said Mr Trimble received 53.4 per cent support at the council meeting.
Delegates were also voting on the main motion which was critical of British and Irish Government proposals released last month despite the IRA's failure to declare that its campaign of violence was over.
Sources said Mr Donaldson received loud applause as he urged council members to take a more hard-line stance on the British and Irish joint declaration.
However, a leadership source said: "At the end of the day, David Trimble's logic has carried it."
Ulster Unionists have been split in recent weeks over the joint declaration released by London and Dublin last month covering a range of issues from policing to criminal justice reform, equality and human rights.
Anti-Agreement UUP members led by Mr Donaldson convened tonight's meeting to force a harder line from the party firmly rejecting the plan.
In particular, they have been critical of proposals dealing with a sanctions body for dealing with parties in breach of the Agreement and a scheme which would enable IRA members who have been on the run since the troubles to return without being jailed.
In the run-up to tonight's meeting Mr Donaldson warned that he would have to consider his future in the UUP if the 900-member council did not reject London and Dublin's joint declaration.
Earlier, Ulster Unionist leader Mr David Trimble arrived at tonight's meeting, saying little.
He urged members of the party not to focus solely on their own concerns. However, the Upper Bann MP said he would listen closely to what party members had to say in tonight's debate.
"We have always operated on the basis of discussion and of consensus," he said. "I hope we will continue to do that."
Any hope of a compromise between the Trimble and Donaldson factions of the in advance of this evening's Ulster Unionist Council (UUC) debate on the Joint Declaration from the Irish and British governments faded this afternoon.
But Mr Trimble will tonight propose a six-point amendment to Mr Donaldson's motion rejecting the joint declaration. The amendments soften opposition to elements in the document but do not imply acceptance of the Joint Declaration either.
Mr Trimble is expected to win tonight's vote, but looks to be facing a tough challenge to prevent the party splitting.
Tonight's meeting is the 11th on issues linked to the Belfast Agreement since 1998.
Mr Trimble has held on to victory by various margins at previous gatherings, but this evening's is certain to inflict a defeat on one side which could well alter the face of the UUP, and by implication, Northern politics.
PA